Abstract: A set of evaluation method for inhibitors selection used in crude distillation unit overhead system was established. Based on the other relevant standards, the methods include: (i) weight loss method (static) to evaluate the inhibition efficiency of inhibitors; (ii) evaluation of film forming performance of inhibitors with saturated sulfate copper solution; (iii) evaluation of emulsification tendency of the inhibitor based on the stability of the emulsion; (iv) dissolution or dispersion properties of inhibitors in oils and waters using water and naphtha as solvents. The inhibitor with 4 best results is the suitable inhibitor. Five inhibitors were screened by the evaluation method. EPR81 has the best performance and is proven by the field application. This indicates that the evaluation method is accurate and effective.

Key words: atmospheric vacuunl distillation unit, inhibitor, selection, evaluation method